None.
This invention relates to fuel delivery components for use with water-cooled internal combustion engines in a marine environment, and more specifically to an integrated fuel system unit including a two-stage water-cooled marine fuel pump, the unit having improved hot fuel and fuel vapor handling characteristics.
In co-assigned U.S. Pat. No. 5,908,020 there is described a water cooled fuel pump for use in marine applications. The pump described therein is a single-stage fuel pump having the advantage of combining the fuel pump, fuel filter, and pressure regulator into a single sealed enclosure in order to, among other things, reduce the space required within a compartment housing the boat engine and its associated components. While the pump assembly solved various problems arising from a grouping in an advantageous manner, other problems still need to be addressed.
A particular problem includes starting the boat in hot weather. At such times, the temperature within the engine compartment can easily reach 135xc2x0 F. and up to 150xc2x0 F. under hot soak conditions. If the boat operator attempts to start the boat at that time, two problems often occur. First, the engine may be difficult to start. Second, even if the engine does start, oftentimes the boat gets only a short distance away from the dock before the engine dies and the boat is adrift.
As described in the referenced patent, water to cool the engine can be drawn into the fuel pump, and circulated through the pump, before flowing to the engine, to cool the fuel flowing through pump. Also, small amounts of water often collect in the fuel circuit assembly and it would advantageous to intermix this water with the fuel circulating through the pump for the fuel/water mixture to be pumped to the engine and burned.
Among the several objects and advantages of the present invention may be noted the provision of an integrated fuel system unit for boats and the like which includes, in combination, a two-stage fuel pump, fuel filter, and pressure relief valve;
the provision of such a unit in which the components are commonly housed to minimize the space required for installation of the housing within an engine compartment;
the provision of such a unit having a water coolant system which optimally cools the fuel pump and fuel flowing therethrough so to prevent hot fuel and vapor lock problems with the engine, particularly at start-up;
the provision of such a two-stage pump in the unit which is capable of providing fuel to the engine under relatively high pressure;
the provision of such an integrated unit to employ a filter between the first stage pump and second stage pump, the filter being a pressurized filter;
the provision of such an integrated unit to re-circulate fuel returned from the pressure regulator and to entrain water accumulating in a chamber where the filter is installed, the fuel and entrained water being pumped to the engine and combusted therein;
the provision of such an integrated unit to be a lightweight assembly with the sealed enclosure in which the pump is housed to be adapted for mounting on the block of the engine; and,
the provision of such an integrated unit which facilitates starting and running of the engine, which improves performance of the engine under a wide range of operating conditions, and which is readily installed and removed for service or replacement.
Briefly stated, the present invention is directed to an integrated fuel system unit incorporating a two-stage fuel pump for marine engines. The fuel pump is installed in a housing together with a fuel filter and pressure regulator. A spiral-wound fuel line composed of a heat-conductive material extends concentrically about the fuel pump to minimize the space required for pump installation in an engine compartment. Water for cooling both the fuel pump and fuel flowing in the fuel line is provided by a cooling system enclosing the pump housing and the fuel line in a sealed chamber through which the water circulates. If an over-pressure condition occurs in the fuel line or fuel rail between the pump and engine, a fuel pressure regulator located between the fuel line and fuel rail returns fuel to a fuel cavity in which the fuel filter is housed, thereby providing a closed loop system. Fuel flow through the pump is such that fuel is pumped through the first stage of the pump, then through the fuel filter and into the second stage of the pump. The bypass fuel returned from the pressure regulator is delivered into the portion of the housing in which the filter is mounted so it can be entrained with fuel now flowing into the second stage of the pump. Any water in the fuel supply line also accumulates in this area so to also be entrained with the fuel and combusted in the engine. Provision of the two-stage fuel pump together with the other components provides cool fuel under high pressure to the engine, facilitates quick starting of the engine, and minimizes the possibility of vapor lock shutting down the engine when the vessel is underway.
The foregoing and other objects, features, and advantages of the invention as well as presently preferred embodiments thereof will become more apparent from the reading of the following description in connection with the accompanying drawings.